Inner ear decompression sickness

Inner ear decompression sickness is damage to the balance organ or the cochlea caused by gas bubbles as a diver returns to the surface. It usually starts with vertigo within an hour or two of surfacing, sometimes with hearing loss or tinnitus. It is a diving emergency, treated with oxygen and recompression in a hyperbaric chamber.

Why it matters for tinnitus

Tinnitus after a dive has two inner ear causes that look alike: this one and inner ear barotrauma, a pressure injury that can tear a membrane and leave a perilymph fistula. The Divers Alert Network (DAN) says the two must be told apart because their treatments differ. Hyperbaric oxygen in a recompression chamber is the standard treatment for decompression sickness, while recompression or any pressure change is contraindicated when inner ear barotrauma is likely. Barotrauma is managed conservatively first, with surgery if symptoms are severe, worsening or not improving.

The line is not always clean. A 2014 review found, from limited case data, that recompression does not appear to cause harm when the diagnosis is in doubt, and a 2018 systematic review stressed that decompression sickness needs early recompression.

What the evidence says

The evidence is observational: case series, comparisons with healthy divers, and systematic reviews built on them.

• Systematic review, 2021. Comparing 397 decompression cases with 183 barotrauma cases, the most useful differences were dive type and breathing gas, depth (a mean of 43 against 13 metres), when symptoms began (on ascent or after surfacing, against on descent), whether balance or hearing was mainly hit, and other decompression symptoms.
• Case series, 2007. Of 18 divers with this condition, 17 had vertigo as the main symptom. Of 26 with barotrauma, none did, and 21 reported tinnitus.
• Case series, 2013. Among 115 recreational divers, symptoms began a median 20 minutes after surfacing and were purely vestibular in 76.5%. A large right-to-left shunt was found in 77%, and 68% of those followed for three months had not fully recovered.
• Meta-analysis, 2023. Across nine observational studies, a right-to-left shunt was linked more strongly with inner ear decompression sickness (odds ratio 12.13) than with the brain (4.96) or spinal cord (2.47) forms. A 2024 series of 61 cases found a shunt in only 31.1%, not a significant excess.
• Mechanism review, 2015. Bubbles in the veins can cross a patent foramen ovale into the arteries. Because the inner ear clears dissolved gas more slowly than the brain, arriving bubbles may grow there while the brain is spared.
• Systematic review, 2026. Of 539 cases treated with hyperbaric oxygen, 37% had symptoms left at discharge and 68% showed dysfunction on testing. Only 46% went on to shunt screening.

What this means for you

• Call your local emergency number for vertigo or loss of balance after a dive that will not settle. DAN says severe vertigo and nausea after diving need emergency care, and to begin surface oxygen if decompression illness is suspected. DAN's medical services page says to contact local emergency services first, then call its hotline on +1-919-684-9111.
• New tinnitus, hearing loss or any dizziness after a dive, even if it settles, needs urgent assessment by a physician who can rule out decompression sickness, as DAN advises; hearing that drops suddenly from any cause is also a same-day matter (sudden hearing loss).
• Report the dive: depth, time, gas, repeat dives, when symptoms began, and any trouble equalising.
• A 2015 joint position statement from two diving medicine bodies says divers who have had inner ear decompression illness should be considered for screening for a patent foramen ovale. Return to diving is a decision for a diving physician.

How it connects

• Diving, flying and ear barotrauma: the pressure injury this must be told apart from.
• Perilymph fistula: the membrane leak barotrauma can cause.
• Sudden sensorineural hearing loss: same-day care for hearing loss from any cause.
• Vertigo, dizziness and tinnitus: other causes of both symptoms together.
• Hyperbaric oxygen therapy: the same chamber offered for chronic tinnitus, where the treatment comparison records no established role.